Optical and Electrical Properties of Single-Crystal GaP Vapor-Grown on GaAs Substrate

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Abstract
Single‐crystal GaP has been grown at rates up to 13 mils (330 μ) per hour onto a GaAs substrate by using a close‐spaced vapor transport technique. The as‐grown layers are invariably n type. Thin layers (3–6 mils, or 75 to 150 μ) grown at slow rates are essentially strain‐free, while thicker layers grown more rapidly exhibit considerable strain. Hall measurements were made and show that the dominant donor has an activation energy of 0.089 eV. Mobilities as high as 120 cm2/V‐sec and carrier concentrations as low as 4×1015/cm3 have been measured. The Hall data imply an effective mass of 0.25m. The decay of pulse‐injected excess carriers indicate a lifetime of about 1 μsec and the presence of several deep traps. Photovoltaic measurements were made and are discussed.